class Lesson():
    """课程类"""
    def __init__ (self,type,time):
        Lesson.type = type
        Lesson.time = time
        print("种类: " + Lesson.type + "时长: " + str(Lesson.time))
    def text(self):  
        grade =  "A" 
        print("我的成绩" + grade)
class student(Lesson): 
    def text(self):       
        grade =  "B" 
        print("我的成绩" + grade)
Lesson1 = Lesson("english",45)
(Lesson1.text())
Lesson2 = student("math",90)
(Lesson2.text())